In the field of x-ray image-assisted, image-guided surgery a physician works with the aid of a navigation system that provides information on the inner body structure of a patient with the aid of intraoperatively produced x-ray images. In such image guided surgery, it is important to precisely identify the moment at which a new image is recorded by the x-ray apparatus. The navigation system has to “know” the moment when the x-ray apparatus recorded a particular x-ray image in order to correctly assign said x-ray image information to corresponding patient position/location data detected by the navigation system.
When using analog x-ray apparatus and/or C-arc x-ray apparatus, the time the image was produced conventionally is detected with the aid of certain hardware components. For example, an x-ray detector can be attached to the image intensifier of a C-arc x-ray apparatus. Whenever an image is acquired, the detector is exposed to x-ray radiation and the corresponding time can be detected. In other conventional systems, a light detector can be attached to the control lamp of the C-arm, and the light detector is activated when an image is acquired. Both methods are hardware-assisted methods that require additional detectors to be attached to the x-ray apparatus. This increases susceptibility to errors and also increases the apparatus hardware.